The present invention relates to flexible covers or tarping systems for open-topped containers and particularly concerns a mechanism for deploying the flexible cover or tarp on the container.
Many hauling vehicles, such as dump trucks, include open-topped containers used for hauling or storing various materials. In a typical dump truck application, the dump body is used to haul a variety of particulate material, such as gravel and the like, as well as organic materials, such as grain or produce.
Depending upon the nature of the materials stored in the open-topped container, it is often desirable to provide a cover for the container. A cover is particularly valuable when the containers are part of a vehicle, such as a dump truck. Rigid covers are well known that may be hinged from one end of the container body and pivoted from an open to a closed position. While rigid covers may be acceptable for stationary containers, the same is usually not true for land vehicles. In this industry, the rigid covers have given way to flexible cover systems. Systems of this type utilize a flexible tarpaulin that can be drawn from a stowed position at one end of the container, to a deployed position covering the open top of the vehicle container or bed. The flexible cover or tarpaulin is preferable in this arena because it can be easily stowed when the cover is not necessary, such as when a dump truck is being loaded or emptied. In addition, the flexible cover is generally easier to deploy than a rigid cover.
A variety of flexible cover or tarping systems have been developed that are geared toward particular hauling vehicle applications. One such tarping system is the Easy Cover® Tarping System manufactured and sold by Aero Industries, Inc. An example of one form of the Easy Cover® Tarping System is shown in FIG. 1. The system includes a tarp deployment mechanism in the form of a U-shaped bail member 22 that is connected at a pivot mount 25 to the base of the container body 13 on vehicle 10. The horizontal section of the U-shaped bail is attached to the tarp 16. The tarp 16 can be preferably stowed by winding onto a tarp roller 19 at the forward end of the vehicle.
The pivot mount 25 and the tarp roller 19 can be of a variety of configurations that permit manual or powered deployment. In one typical installation the pivot mount 25 includes a torsion spring pack that is biased to rotate the bail member 22 (clockwise in the figure) to pull the tarp 16 over the top of the container 13. The tarp roller 19 is biased to resist this rotation of the bail member. In some versions, a manual crank rotates the tarp roller 19 to allow the tarp 16 to unfurl under the torsion force of the spring pack. In other versions, a motor controls the rotation of the tarp roller. The manual crank or motor are rotated in the opposite direction to pull the bail member 22 toward the front of the container body 13 and to thereby stow the tarp 16 in its open position.
One risk that is sometimes faced with tarping systems of the type shown in FIG. 1 is a potential mechanical failure of the bail member 22. Particularly, as discussed above, the pivot mount 25 includes a torsion spring pack that is biased to rotate the bail member 22. The torsion spring pack applies a torque (clockwise in the figure) at a first end 27 to the bail member 22, which causes rotation (clockwise in the figure) of the bail member 22. The rotation of the bail member 22 is stopped when a second end 29 of the bail member 22, which is connected to the tarp 16, brings the tarp 16 into contact with the top of the container 13.
When the tarp 16 is in this deployed position, the torsion spring pack continues to apply torque to the bail member 22, thereby inducing stresses in the body of the bail member 22. As the tarp deployment mechanism ages, these stresses, in combination with environmental wear and other factors, can lead to fractures in the bail member 22. Fractures in the bail member 22 can also occur in a collision involving the vehicle 10. In most cases the fractures are minor and noticeable to the vehicle owner/operator who can replace the affected component. However, in some cases the fracture is not evident or is relatively immediate, and in extreme cases the fracture leads to a failure or breakage of the bail member. In the event of a breakage of the bail member 22, a portion of the bail member 22 that remains attached to the pivot mount 25 can freely rotate. The torsion spring pack causes the portion of the bail member 22 that remains attached to the pivot mount 25 to rotate rapidly and forcefully, which presents a danger to any person or thing in the path of the bail member.
Although the risks of mechanical failure can be mitigated through proper maintenance and periodic inspection of the tarp deployment mechanism, there remains a need for a tarping system with improved safety in the event of mechanical failure.